1. Field of the Invention
The invention relates to a buttonhole sewing machine for the production of a group of buttonholes on a workpiece, the group having at least two buttonholes of varying design and/or size, the buttonhole sewing machine comprising a needle, which is mounted in an arm, and which is drivable to reciprocate in a Z direction by means of a driving motor, and which is drivable by a jogging drive for the production of a zigzag seam by a motion of the needle relative to the workpiece, and which is drivable to pivot about an axis by means of a pivot drive; a hook bearing, which is disposed in a base plate, and which is drivable by a pivot drive to pivot synchronously and equiangularly of the needle about a pivot axis which extends in the Z direction; a hook, which is disposed in the hook bearing; a stitch hole, which is allocated to the needle and the hook; a holder for the workpiece, which holder is displaceable by drives in an X direction and a Y direction; and an operating and control unit.
2. Background Art
In a buttonhole sewing machine of the generic type known from U.S. Ser. No. 09/063,965, U.S. Pat. No. 6,006,685 the workpiece holder in the form of an X-Y table is actuated by two stepper motors. Furthermore, the needle bar and the hook bearing are driven synchronously and equiangularly by a stepper motor so that the sewing tools are rotatable about the axis of the needle, which helps attain a constant position of the sewing tools relative to the direction of sewing and thus considerable flexibility of the machine as regards the geometry of the seam.